KVM: MMU: Fix mmu_shrink() so that it can free mmu pages as intended
Although the possible race described in commit 85b70591 KVM: MMU: fix shrinking page from the empty mmu was correct, the real cause of that issue was a more trivial bug of mmu_shrink() introduced by commit 19526396 KVM: MMU: do not iterate over all VMs in mmu_shrink() Here is the bug: if (kvm->arch.n_used_mmu_pages > 0) { if (!nr_to_scan--) break; continue; } We skip VMs whose n_used_mmu_pages is not zero and try to shrink others: in other words we try to shrink empty ones by mistake. This patch reverses the logic so that mmu_shrink() can free pages from the first VM whose n_used_mmu_pages is not zero. Note that we also add comments explaining the role of nr_to_scan which is not practically important now, hoping this will be improved in the future. Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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